Application of broad-spectrum pesticides is the primary method used for controlling fungal pests. Such application has resulted in significant environmental pollution and ecological disruption. Pesticide residues are found in food and groundwater and often eliminate beneficial organisms resulting in emergence of secondary pests. Furthermore, as the target pests become less susceptible to the pesticide, there can be a resurgence of the original pest, requiring application of excessive quantities of pesticides for control. This has resulted in a search for environmentally safer methods including biological control involving targeting an attribute that is pest specific and the use of synergistic combinations of fungicides to reduce the amounts of application.
One target that has been selected is the structural polymer chitin which is present in insects and some fungi that attack plants, but is absent in higher plants and vertebrates.
Suslow et al U.S. Pat. No. 4,751,681 contains claims directed to preparing bacteria for producing chitinase for the purpose of inhibiting plant pathogens.
Suslow et al U.S. Pat. No. 4,940,840 contains claims directed to introducing a DNA sequence encoding for the production of chitinase into plants so they are pathogen-resistant.
Harman et al U.S. Pat. No. 5,173,419 teaches obtaining purified endochitinase and chitin 1,4-.beta.-chitobiosidase (referred to therein as exochitinase) from Trichoderma harzianum strain P1 having accession No. 74058 and use of the endochitinase to inhibit the germination and subsequent growth of chitin-containing fungi.
Harman et al U.S. patent application Ser. No. 07/919,784 teaches obtaining purified endochitinase and chitin 1,4-.beta.-chitobiosidase (referred to therein as chitobiase) from Trichoderma harzianum strain P1 having accession No. 74058 and use of these to inhibit germination or replication of chitin containing fungi and antifungal synergistic combinations of endochitinase and chitin 1,4-.beta.-chitobiosidase (referred to therein as chitobiase).
Harman et al U.S. patent application Ser. No. 07/990,609 is directed to antifungal synergistic combinations of fungal cell wall degrading enzyme and non-enzymatic fungicide, and Harman et al U.S. patent application Ser. no. 08/012,945 is directed to antifungal synergistic combinations of purified cell wall degrading enzyme and antifungal bacteria. Both of these teach obtaining purified glucan 1,3-glucosidase from Trichoderma harzianum strain P1 having accession No. 74058 for the cell wall degrading enzyme.